Knowledge Bank

The weakly attractive interatomic potential between a refractory metal and a rare gas atom is explored by direct spectroscopic access of rovibronic levels in the AlAr van der Waals complex. Mass-resolved resonance-enhanced multiphoton ionization is used to probe the spectral region about the $Al2S1/2-2P1/2$ transition. A vibrational progression in the AlAr $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\sigma +$ state is identified on the $AlAr+$ mass channel. Lower limits for binding energies in the $X2\Pi 1/2$ and $B2\Sigma +$ states are found to be 133 and $373cm-1$, respectively. Results are compared to earlier work on NaAr.